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Engineering a new solution to single-use plastic pollution

Plastic pollution is reaching crisis level. Of the 1 million plastic bottles sold every minute across the globe, only 14% are recycled. The vast amount of unrecycled plastic that ends up in our oceans contaminates marine ecosystems and harms ocean life.

A huge part of the problem is the strong plastic used in drinks bottles: polyethylene terephthalate (PET). It currently takes hundreds of years for PET to break down naturally in the environment.

But now a team, led by our own Professor John McGeehan and Dr Gregg Beckham of the US Department of Energy, has created a new mutant enzyme that breaks down plastic bottles faster. Their modified version of the PETase enzyme – first discovered in a Japanese waste dump in 2016 – starts breaking down plastic in days. The discovery could revolutionise the recycling process and help solve one of the planet’s biggest environmental issues.

The breakthrough took place after the team examined PETase's structure at Diamond Light Source, near Oxford – where intense X-rays 10 billion times brighter than the sun revealed its individual atoms. The structure of the enzyme was similar to one evolved by many bacteria to break down cutin – a natural polymer used as a protective coating by plants. The team manipulated the enzyme to explore this connection – and found they had improved its ability to eat PET in the process.

A patent for the enzyme has been filed, and now Professor McGeehan and team – which includes our PhD student, Harry Austin – are working on improving it for industrial use, as a sustainable recycling solution.

The research shows that the enzyme is not yet optimised. John says this gives scope ‘to use all the technology used in other enzyme development for years and years and make a super-fast enzyme.’

He says, ‘There is an urgent need to reduce the amount of plastic that ends up in landfill and the environment. I think if we can adopt these technologies we actually have a potential solution in the future to doing that.’

The ongoing research is supported by the development of a new 'Centre for Enzyme Innovation' which, in partnerships with industry, will have the capacity to address this global challenge.